Why Did Hms Hood Explode ?

timmymagic said:
airman said:
Drachinifel and Oceanliner designs said same things !
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Given when Drachinifel published his video (2 years ago) and when Oceanliner designs did (8 days) I suspect that we can guess how that 'coincidence' happened...
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When you explain reconstructions of historian facts i cannot speak about exclusivity : it's not a commercial product.
 
FWIW, the 'short burrowed beneath belt' almost harks back to Drake & Nelson, when trashing opponent's top-hamper to allow capture and catching opponent on water-line during up-roll to flood were enjoyed, um, employed...
 
One that isn't brought up in all this, that I believe is also relevant and possible, is the culprit shell penetrated the upper armor (7") and then struck the armored deck. An overmatch of the shell to the armor occurred causing the armored deck to rupture and spraying hot fragments into the compartment(s) below. The shell itself doesn't penetrate the deck, just breaks a hole in it by sheer weight and energy, then ricochets off. This might be followed by the shell going off as the fuze initiated upon penetrating the intermediate belt. Some of that explosion vents through the shattered hole in the deck and is sufficient to initiate a magazine fire--either 4" or 15" magazine. The result is the same.

This is an example of what I mean from Jutland:

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A heavy shell hit the turret roof, failed to penetrate, but shattered the armor and sprayed the interior with fragments.
 
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When I asked about that to write an article, an armor expert told me that the deflection angles of the Hood's armor were miscalculated, to save weight.
 
timmymagic said:
Given when Drachinifel published his video (2 years ago) and when Oceanliner designs did (8 days) I suspect that we can guess how that 'coincidence' happened...
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Hi,
Although I generally like Drachinifel's videos (even if he can sometimes seem to take a long way round when saying something) I'm not yet convinced of his analsis in this video. Overall I'm not saying that I believe that he is wrong but rather I'm just not ready yet to accept his statement that this is "the most likely explanation" as to why HMS Hood exploded. Overall I think that he did a very good explanation of why he believes in the theory that he proposed, but I still have questions about a few items and as such am not ready to fully accept it yet as the "most likely explanation".

Specifically, one particular issue is whith regards to the machinery space that he belives was penetrated. In looking at information on HMS Hood it appears that this was a fairly densely packed space, with what appears to be some very heavy machinery right about where he shows the notional location of where he thinks a hit may have occurred. As such, I think that a closer look would need to be made of "anything that may have stood in the path" of a shell entering this machinery space along its supposed path to the bulkhead between the machinery space and the 4in magazines before I would feel comfortable with the assumption that a shell through this space in this location could have penetrated the intervening bulkhead. Or put another way, while I believe that his theory sounds resonble and appears to be well researched, right now I think that there are still too many unknowns to fully accept it as the "most likely."

Regards

Pat
 
airman said:
https://www.britannica.com/topic/HMS-Hood - in topic of Britannica there are also a damage of propeler shaft that caused a spark that ignited munitions store.
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That strikes me as really reaching. There's no way Hood took a hit that would damage her propeller shaft before the fatal hit. She'd only sustained damage on deck by that point - fire in the ready-use AA ammo, and had only been under fire for seven minutes. If he's presuming shaft damage caused by close misses, then there's no route for the supposed fire to get into the magazine.
 
Speaking English as a Basque Spanish it is translated by Reverso that I deliver this excerpt from Wikipedia in French. I am not a marine specialist but I have worked on the cannons ... This is an element of explanation. The Hood was less armored than a conventional battleship to gain weight ... And when you know what a shell armour is worth, it’s reasonable to think that the dice were thrown since the Hood was laid in 1916 ...
The battlecruiser is a type of warship that appeared in the early 20th century. Its characteristics are similar to those of the battleship for the movement, the calibre of the main artillery, the size of the crew, the range of action, but its speed is much higher, exceeding that of the largest cruisers of the time, thanks to a slimmer length-to-width hull and a more powerful propulsion system. This additional weight is offset, on the British design ships, by a lighter armor, and this less protection is the main restriction to the use of this type of ship as shown by the main battles they take part in during the First World War.
 
DWG said:
That strikes me as really reaching. There's no way Hood took a hit that would damage her propeller shaft before the fatal hit. She'd only sustained damage on deck by that point - fire in the ready-use AA ammo, and had only been under fire for seven minutes. If he's presuming shaft damage caused by close misses, then there's no route for the supposed fire to get into the magazine.
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I suspect of direct hit fired in to the magazine.
 
Tonton-42 said:
This additional weight is offset, on the British design ships, by a lighter armor, and this less protection is the main restriction to the use of this type of ship as shown by the main battles they take part in during the First World War.
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We can rule this out as well-informed by the implied claim that light armour led to the loss of the battlecruisers at Jutland. It's been accepted in English-language sources since at least the 80s that the real cause was the appalling magazine safety practises encouraged by Beatty in the Battle Cruiser Flotilla/Fleet - light armour was the cover-up, not the true cause.

In fact Hood was only slightly less heavily armoured than the Queen Elizabeths or Rs, with 12" belts vs 13", deck armour for Hood and the QEs was 1-3", 1-4" on the Rs.

While the reconstructed QEs got improved deck armour as part of the rebuild, the unreconstructed Valiant did not. So while Hood had less deck armour than most British battleships of WW2, there were exceptions.
 
DWG said:
We can rule this out as well-informed by the implied claim that light armour led to the loss of the battlecruisers at Jutland. It's been accepted in English-language sources since at least the 80s that the real cause was the appalling magazine safety practises encouraged by Beatty in the Battle Cruiser Flotilla/Fleet - light armour was the cover-up, not the true cause.

In fact Hood was only slightly less heavily armoured than the Queen Elizabeths or Rs, with 12" belts vs 13", deck armour for Hood and the QEs was 1-3", 1-4" on the Rs.

While the reconstructed QEs got improved deck armour as part of the rebuild, the unreconstructed Valiant did not. So while Hood had less deck armour than most British battleships of WW2, there were exceptions.
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Was the Hood killed because of the statistics rather than because of its lack of armor ? Without wanting to make a bistro philosophy the great warships are impressive but it must be admitted that their effectiveness in naval combat seems quite low. Let me explain. The number of shots scored in naval battles before the appearance of firing lines and other modern electronic aids is low. Some % ... More than 700 shells (15 and 16” ! 2800 of all calibres with a ratio for the set of 1/7 shots to goal, the final hallali surely increasing the ratio) and dozens of torpedoes were needed to sink the Bismarck although it was unable to maneuver ... However, it only takes 2 to 3 shots at the goal of a well-placed large-calibre shell to "kill" one of these monsters because in the eternal duel cannon/ armor were the best designed armour are never sufficient ... And I suppose for the Hood when bad luck, or lack of foresight (?) gets involved it is often a disaster.
 
I'm extremely sceptical. A battleship blown up by a spark from its propeller shaft?!? That would be the flukiest fluke, more fluky than a lucky 15in shell hit.

People can come up with theories and waffle any old technobabble about how they are right safe in the knowledge what they say can never be proved or disproved.
Sometimes I wonder whether it's the echoes of a coping mechanism since 1941 to avoid blaming a direct (but lucky) hit from a German shell.
 
Martin Lawrence is the person who put forward the theory:
historyfirst.com

HMS Hood 'sunk by mechanical failure, not Bismarck' - History First

It was the most shocking loss of a Royal Navy warship in the Second World War, and may have been completely misunderstood. HMS Hood did not sink due to a "lucky hit" from the German battleship Bismarck, but as a result of catastrophic metal fatigue, a new paper suggests.
historyfirst.com historyfirst.com
He believes the true explanation has been hiding in plain sight — in eyewitness testimony from Able Seaman Robert Tilburn that was given at the second inquiry and effectively ignored. Tilburn, a Yorkshireman who was 20 years old at the time of the sinking, said that “after Bismark’s second salvo fell [close to Hood but not hitting] the vessel was shaking with a great vibration.”

According to Lawrence, the only way that a ship as large as Hood‘s 48,000 tons could be made to shake like this was through a serious fault in its propulsion system. In his analysis, this most likely involved a propellor shaft breaking out of its bearing mounts and windmilling about until it broke. In his paper, he writes: “There is just nothing else on the ship with sufficient power to do this and there is no reason for Tilburn to make this up; in the disaster that was about to unfold around him, this was something unusual enough that he specifically remembered it.”

Crucially, Hood‘s inner propellor shafts passed within five feet of the main magazines at the rear of the ship, with their 112 tons of explosive cordite. Lawrence continues: “Each of her four propeller shafts was responsible for pushing some 12,000 tons of Hood along, in a storm, at 28 knots; a quite immense amount of power. Any breakage of these shafts or their bearing mounts, themselves of heavy and solid construction, would cause large and quite massive metal pieces, probably hot from explosively disintegrating, to go flying about. These parts would easily have enough energy to smash through local steel walls and with the magazines so close it is inevitable that these would be penetrated in a shower of red hot sparks.”

In Lawrence’s analysis, these sparks would likely have set alight bags of cordite, causing a fire that spread rapidly. At the same time, the flailing propellor shaft would have reamed open the bulkhead between the engine room and the magazines and shaft tunnels at the rear of the ship. Fire and smoke would have been drawn through the engine room, exiting by the main ventilation trunk near the mainmast — the exact position of the column of flames observed from Prince of Wales.

At this point, Hood would have been doomed, but most of the crew would have had no idea of what was happening and Lawrence believes that efforts to return fire on Bismarck hastened the British ship’s end. Specifically, reloading the guns in one of two stern turrets that were seen to fire, would have involved opening anti-flash doors. This would have allowed far more air to flow into the magazines, then out through the hole in the engine room bulkhead and up via the ventilation system to leave the ship.

Such a fire tunnel would lead to further acceleration of the blaze and, only seconds later, to the explosion of the whole stock of cordite, almost vaporising a large section of the ship.

Lawrence said the whole sequence of events would have taken between 90 to 120 seconds from the damage occurring after Bismarck‘s second salvo to the vessel exploding — compared to the Admiralty’s timescale of a couple of seconds between the shell hit and the column of flames and a few more seconds before the explosion.

According to Lawrence, the break in the propulsion system was most likely caused by a part failing to due metal fatigue. As he writes: “Metal fatigue is insidious and can be extremely hard to detect until it is too late.” The immediate triggers could have been the enormous strain the ship was under during the pursuit and combat, the shock wave from a near miss in the sea by a German shell, or a combination of the two. Thermal factors may also have played apart, with the propellor shaft mounts close to both the hot engine room and the very cold Atlantic water.

Ultimately, however, metal fatigue would have resulted from the ship’s poor condition, which Lawrence said was abundantly documented. At the time of the battle, Hood — under construction from 1916, launched in 1918 and commissioned in 1920 — was arguably barely seaworthy. A refit that was planned for 1939 had been postponed by the outbreak of war and the ship was affectionately referred to as the fleet’s “largest submarine”. Hood not only leaked in all but the calmest seas but was visibly rusty. The condensers — a crucial part of the propulsion system — required urgent repairs after a very near miss by a German bomb in September 1939 and some other components were repaired, but not replaced, in the spring of 1940.

Most significantly, one of Hood‘s turbines partially failed following the attack on the French fleet at Mers-el-Kébir in July 1940.

In Lawrence’s analysis, six dockyard visits for heavy repairs during the two years before the sinking amounted to “patching up” rather than thorough overhauls. He said: “Hood‘s machinery was 20 years old and much of it was known to be in a severely worn state. Not only this, but the hull itself had required patching and re-riveting in three dockyard visits. This brings into question the security of the footings — the points at which this heavy, powerful, but elderly, machinery was fixed into the ship’s frame and exactly how secure it was.

“Given the wear and tear, some corrosion of parts, then the hammering explosions nearby of Bismarck‘s shells, a train of events can be envisaged where one of the bearing mounts supporting the propellor shaft fails and the unsupported shaft initially sags but, as it is being driven by the turbine, flails about, causing the heavy vibration reported to the inquiry. In flailing, it penetrates the magazine walls and starts the fire that ultimately condemns Hood.”

He believes it is especially surprising that the boards of inquiry didn’t consider mechanical failure as a possible cause of the loss, given that, in 1939, the First Sea Lord, Sir Dudley Pound, was recorded as saying: “The likelihood of her (Hood) being able to steam at high speed for any length of time was considered remote.”

The dash to intercept Bismarck took 50 hours, with Hood travelling at 25 knots or more into increasingly rough seas. Pound may well have been more prescient than he knew. Lawrence points out that, during her last hours, Hood was being driven to the very limit, both in reaching Bismarck and in manoeuvring to engage — so much so that even the new Prince of Wales could hardly keep pace. The 20-year-old machinery on board Hood was being worked flat out.

In not considering mechanical failure, was the Admiralty deliberately covering up? Lawrence doesn’t think so. He said: “I just don’t think they thought about it. I think they wanted to come to the conclusion that matched Jutland, rather than Hood. I think that clouded their thinking and they became very myopic. They had lost Hood and within four or five hours people at the Admiralty were talking about a repeat of Jutland — that suggestion fixed itself in their heads.”

Today’s naval experts are more open-minded, according to Lawrence. He said: “When I presented my paper in Newcastle, I had three letters from retired Royal Navy officers — two rear admirals and an engineering commander — saying they knew that the Hood–Bismarck theory was wrong and thanking me for putting forward this alternative explanation.”

He said that another factor inadvertently influencing the navy’s original findings may have had to do with honour. “That outcome suited the psyche. Hood was a warship built to go into battle against His Majesty’s enemies and was lost in combat. So there was kind of glory to it as well. I think that also affected the thinking. But it doesn’t really match up with what people saw.”

Given the old idea that Bismarck sank Hood, the British ship was considered to have been avenged on 26-27 May when Bismarck was crippled by sustained Royal Navy attacks in the Atlantic and scuttled. If Lawrence is right, the whole story is just as tragic but less neatly resolved.

So why is it important to revisit all this, more than 80 years after the event. Lawrence said: “There’s a lot of supposition made because this sinking happened in history and ‘history repeats itself’. But it just doesn’t. What I set out to consider was the operational situation in its entirety and that included the mechanical condition of HMS Hood. Having been involved in metal fatigue and metallurgy quite a lot in my working life, once you take into account Hood‘s recent record of heavy repairs and the age and worn down condition of her machinery then ask whether metal fatigue might have played a part in the loss, lo and behold, the scales fall from your eyes.

“As Roskill pointed out, we will never know for certain what caused the loss of Hood, but it was widely known among the senior naval officers of the day that she needed fully rebuilding. The Admiralty should have included the possibility of metal fatigue in their deliberations.”
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More at the link.
 
Number of problems with that analysis:

-Numerous recorded cases of explosion onboard or nearby underwater explosion causing significant vibration of the entire ship, so the assertion that "a serious fault in the plant" is the only source of vibration is completely false.

-Mechanical failure just plain doesn't work the way imagined here. Failure of a shaft is possible, through incredibly rare, however it's not going to explode, flail violently around, etc. etc., but instead break in torsion. Local damage is possible, but smashing into other compartments is pretty much impossible. Likewise, "hot from explosively disintegrating" it's just flat out absurd.

-Shafting and structure is almost invariably life of ship with no maintenance required beyond repair of bearing journals. Consequently, the ship being older has no meaningful bearing of shaft failure. Failure of turbines, gearing, bearings, coupling bolts, etc. is far more likely if the plant was to fail from age or overwork.

-If you assume for the sake of argument that shaft failure and flailing is possible, it's going to cause damage all the way around as well as throughout the shaft run. In other words, if it smashed into the magazine, it's probably smashing through the hull as well, and very likely there's damage to stern tube seals. This likely causes immediate major flooding and would quench any fire.

-Likewise, a flailing shaft would act like a large flat hammer, causing damage to framing and dents/impact damage to plating, but isn't likely to cause penetration damage. Failed seams are certainly possible, but the majority of the plating would remain intact, and the shaft/damaged structure remains in shaft alley. Consequently, any sparks are almost certainly staying in the shafting space.

-Ignition of a bag of cordite takes quite a lot of energy. A single spark isn't going to do it. A large enough quantity of sparks perhaps could, though more likely it would first cause the bag to smolder and could easily be put out by the crew.

-The degree of improbable events occurring in sequence for an explosion to occur as a result of a mechanical shaft failure is the next best thing to impossible to begin with, and having it occur precisely at the exact moment in time when she's in a gun dual is utterly absurd.
 
sdmuleman said:
Number of problems with that analysis:

-Numerous recorded cases of explosion onboard or nearby underwater explosion causing significant vibration of the entire ship, so the assertion that "a serious fault in the plant" is the only source of vibration is completely false.

-Mechanical failure just plain doesn't work the way imagined here. Failure of a shaft is possible, through incredibly rare, however it's not going to explode, flail violently around, etc. etc., but instead break in torsion. Local damage is possible, but smashing into other compartments is pretty much impossible. Likewise, "hot from explosively disintegrating" it's just flat out absurd.

-Shafting and structure is almost invariably life of ship with no maintenance required beyond repair of bearing journals. Consequently, the ship being older has no meaningful bearing of shaft failure. Failure of turbines, gearing, bearings, coupling bolts, etc. is far more likely if the plant was to fail from age or overwork.

-If you assume for the sake of argument that shaft failure and flailing is possible, it's going to cause damage all the way around as well as throughout the shaft run. In other words, if it smashed into the magazine, it's probably smashing through the hull as well, and very likely there's damage to stern tube seals. This likely causes immediate major flooding and would quench any fire.

-Likewise, a flailing shaft would act like a large flat hammer, causing damage to framing and dents/impact damage to plating, but isn't likely to cause penetration damage. Failed seams are certainly possible, but the majority of the plating would remain intact, and the shaft/damaged structure remains in shaft alley. Consequently, any sparks are almost certainly staying in the shafting space.

-Ignition of a bag of cordite takes quite a lot of energy. A single spark isn't going to do it. A large enough quantity of sparks perhaps could, though more likely it would first cause the bag to smolder and could easily be put out by the crew.

-The degree of improbable events occurring in sequence for an explosion to occur as a result of a mechanical shaft failure is the next best thing to impossible to begin with, and having it occur precisely at the exact moment in time when she's in a gun dual is utterly absurd.
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That's the problem with this scenario. PoW suffered something like this during its sinking. One shaft was damaged and bent but kept running. The major result was flooding of the entire shaft alley then adjoining compartments. The shaft if you had a mechanical failure, like a bearing seizing up, or the like, is simply going to wipe the bearing with a resulting vibration in the shaft that would force the engine to be shut down. The shaft also is not one continuous piece of tubing but assembled in sections. It's likely that if over-torqued the bolts at some point in the shaft assembly would shear first.
 
Agreed that a shaft problem would not cause an explosion, but would cause SEVERE flooding.
 
This guy is seriously arguing that the inner prop shaft failed due to metal fatigue 10 minutes into the battle despite the ship having been running at 28kt since 03:00 (a full 3 hours) and arguing that the probability of this occurring is higher than a 15in shell hit in the right place??

It's absurd. If Hood had blown up suddenly an hour before the battle then I agree we'd have a very odd case to look at, but given the (literal) smoking guns of Bismarck I think its pretty easy to find the culprit.
I suspect whatever chain of events occurred that unstable cordite was at the bottom of it.

Interestingly, although David Mearns and Eric Grove in 2001 postulated that the aft flash had passed via the starboard fuel tanks forward along the hull to detonate the forward magazines, in a later documentary (filmed around 2012ish I think) that I saw recently they seemed to think that the forward magazines went up after the bow section tilted upwards. Given that Barham detonated (another officially attributed case of 4in ammo cooking off the 15in magazines) shortly after capsizing its likely that unstable toppling cordite went off - especially if Hood still had any MD cordite charges aboard. The fact that all of Hood's main magazines detonated indicates something serious, its likely even if the forward magazine had been hit first that the results would have been equally catastrophic.
 
I thought to dig up the theory behind the first mentioning of sparks causing Hood to explode.
With a hammer in your hand, all the world looks like a nail.
Martin Lawrence sought an explanation in his own field of expertise:
Having been involved in metal fatigue and metallurgy quite a lot in my working life
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His explanation can't be proved, can't be disproved.
I have little or no expertise in these matters. After reading and rereading the comments here, following Occam's Razor, I am still favouring Bismarck's lucky hit.
 
Hood said:
This guy is seriously arguing that the inner prop shaft failed due to metal fatigue 10 minutes into the battle despite the ship having been running at 28kt since 03:00 (a full 3 hours) and arguing that the probability of this occurring is higher than a 15in shell hit in the right place??

It's absurd. If Hood had blown up suddenly an hour before the battle then I agree we'd have a very odd case to look at, but given the (literal) smoking guns of Bismarck I think its pretty easy to find the culprit.
I suspect whatever chain of events occurred that unstable cordite was at the bottom of it.

Interestingly, although David Mearns and Eric Grove in 2001 postulated that the aft flash had passed via the starboard fuel tanks forward along the hull to detonate the forward magazines, in a later documentary (filmed around 2012ish I think) that I saw recently they seemed to think that the forward magazines went up after the bow section tilted upwards. Given that Barham detonated (another officially attributed case of 4in ammo cooking off the 15in magazines) shortly after capsizing its likely that unstable toppling cordite went off - especially if Hood still had any MD cordite charges aboard. The fact that all of Hood's main magazines detonated indicates something serious, its likely even if the forward magazine had been hit first
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On wikipedia english about Hms Hood an adiacent hit to 4 in ammo or 15 in magazines could be a first probably reason of catastrophic explosion. https://en.wikipedia.org/wiki/HMS_Hood
 

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